/in/foo.cc: In function 'void built(int, int, int)':
/in/foo.cc:6:25: warning: suggest parentheses around '+' inside '<<' [-Wparentheses]
 #define rson m+1,r,rt<<1+1
                        ~^~
/in/foo.cc:44:8: note: in expansion of macro 'rson'
  built(rson);
        ^~~~